HTTP status code 500 indicates an internal server error. Something is wrong with the instance, not with Summit.
Summit
Community to discuss Summit, a Lemmy reader for Android.
App (Play Store): https://play.google.com/store/apps/details?id=com.idunnololz.summit
APK: https://github.com/idunnololz/summit-for-lemmy/releases
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Website: https://summit.idunnololz.com/
Have you tried a smaller file size? Weird that it didn't even work with image links.
Tried and can't even select a photo, it gets stuck like this:
If it's via URL then you are not uploading anything so that shouldn't fail with an upload error. If you are seeing that error with a URL please report that because that's a bug.
That being said because this is a 500 it's hard to tell what the issue is. I have found that the Lemmy servers are picky with images and will fail for some reasons such as:
- image format is not supported (eg. trying to upload a heif image)
- image resolution not supported (either the width or height of your image is too large)
As a potential workaround you can try upload images to imgur. To enable this go to Settings > Misc > Use Imgur.